Differential Acoustic Spectroscopy (DARS)
Acoustical Resonance Spectroscopy (DARS) exploits the low frequency resonance
(~1000 Hz) of a fluid column to measure the bulk acoustic properties of a small
sample of rock and other material. First, we measure the resonant frequency
spectrum of a fluid-filled but otherwise empty cavity. Next, we introduce a
small sample of rock into the cavity and measure the changes in resonances,
both frequency and Q. The changes are then inverted to estimate the modulus and
Q of the sample. The first generation of DARS operates at atmospheric
pressure. The drawing above shows a new generation of DARS that measures
acoustic properties of a rock sample under high pressure.
Harris, J.M, Quan, Y. and Xu, C., Differential Acoustic Resonance Spectroscopy: An experimental method for estimating acoustic attenuation in porous media, SEG Expended Abstracts, 2005
Wang, S., J. Zhao, Z. Li, J.M. Harris, & Y. Quan, 2012, Differential Acoustic Resonance Spectroscopy for Acoustic Measurement of Small and Irregular Samples: Journal of Geophysical Research, VOL. 117, B06203.